Liquid pressure supply system



Oct. 8, 1963 s. R. TYLER 3,106,165

LIQUID PRESSURE SUPPLY SYSTEM Filed June 13, 1961 I N VEN7 OK STANLEY K' "WLEK BY MwM United States atent 3,106,165 Patented Oct. 8, 1963 3,106,165 LIQUID PRESSURE SUPPLY SYSTEM Stanley R. Tyler, Chelteuharn, England, assignor to Dowty Fuel Systems Limited, Cheltenham, England Filed June 13, 1961, Ser. No. 116,823 Claims priority, application Great Britain June 15, 1960 1 Claim. (Cl. 103-97) This invention relates to centrifugal pumps for supplying pressure liquid to a hydraulic load and arranged for a controlled liquid flow into the pump inlet so that by virtue of the pump diameter and/ or of the driving speed a central cavity or core is formed around the inlet substantially at the vapour pressure of the liquid. This arrangement of 'a centrifugal pump forms the subject of my co-pending patent application, No. 80,967, filed January 4, 1961.

In accordance with the present invention a centrifugal pump for applying pressure liquid to a hydraulic load from a low pressure source includes a throttle valve balanced with regard to the low pressure for controlling liquid flow into the pump, the throttling portion of which is located within or closely adjacent to the centre of the pump impeller. Preferably the throttle valve includes one or more discharge ports, each arranged to produce a radial stream of liquid within the impeller to reduce the extent of liquid atomization. The hydraulically balanced throttle valve may comprise a cylindrical sleeve slidably mounted in a fixed sleeve around which the impeller rotates, the fixed sleeve having one or more radially directed ports in its wall within the impeller which is, or are, partially closed by the cylindrical sleeve, liquid flowing through the cylindrical sleeve to obtain access to the ports and sliding movement of the cylindrical sleeve serving to adjust the effective size of the ports and thus the throttling effect. The cylindrical sleeve is preferably rotated continuously to reduce frictional resistance to sliding thereof.

One example of the invention will be described with reference to the accompanying cross-sectional drawing. In this drawing within the pump casing 1 a circular pump recess 2 is provided within which a shrouded centrifugal pump impeller 3 is located. The pump impeller is driven by a drive shaft 4 which is sealed by seal 5. Cylindrical portions 6 and 7 at either end of the impeller also form seals in corresponding recesses in the pump casing to prevent leakage of the liquid from the recess 2. Centrally of the impeller 3 a cylindrical recess 8 is located opening adjacent to the end of the impeller containing the sleeve 7. A fixed sleeve 9 extends from the casing 1 into the recess 8 and within this sleeve a pair of throttle ports 11 are provided which open into the passage 12 within the impeller 2. Slidably mounted within the casing 1 is a cylindrical sleeve 13 which enters within the sleeve 9 and whose lefthand end is arranged to close partially the ports 11. The passage through the sleeve 13 ensures substantially equal pressure at either end and thus substantial hydraulic balance of the sleeve in the axial sense. Within an opening 14 in the casing, a pinion 15 is formed on the sleeve 13 which is in mesh with a driving gear 16, also located within recess 14 so that the sleeve 13 is continuously rotated about its longitudinal axis without varying the effective area of the ports 11. A cylinder 17 also located in the casing 1 co-axially with the sleeve 13 is engaged by a piston 18 formed on sleeve 13, a spring 19 urging the spring 13 in a direction to uncover the ports 11. Hydraulic connections 21 and 22 extend to either end of the cylinder 17 and hydraulic pressure diiference between the pipes 21 and 22 will control the position of sleeve 13 in conjunction with spring 19 by moving the sleeve 13 in a direction parallel to its longitudinal axis. The rotational drive applied to the sleeve 13 reduces frictional resistance to movement of the cylindrical sleeve in the fixed sleeve and also of piston 18 in cylinder 17 so that the position of the sleeve 13 is extremely accurate in response to change in smalldifferences of pressure between pipes 21 and 22. Liquid at low pressure from any convenient source is supplied to a port 23 at the right-hand end of the sleeve 13. Flow of liquid through the pump is controlled by the throttling elfect of the sleeve 13 relative to the ports 11 and pump liquid leaves the pump through a diffusing chamber 24.

In operation the pump is driven at a sufficient speed to ensure that a cavity or hollow core is formed in liquid within a central annulus adjacent to the sleeve 9 within the impeller 2, and that liquid flowing from the ports 11 form solid streams which flow radially outwards to meet the annulus of liquid within the impeller.

I claim as my invention:

A centrifugal pump for supplying pressure liquid to a hydraulic load from a low pressure source including a .centrifugal pump impeller, variable throttle valve means having a variable throttle aperture located centrally of the pump impeller for controlling liquid flow into the pump, said variable throttle valve means being hydraulically balanced with regard to the low pressure and also including a sleeve movable in a direction parallel to the longitudinal axis of the sleeve for varying the size of the aperture, means for moving the sleeve in a direction parallel to the longitudinal axis of the sleeve, and rotary drive means for continuously rotating the sleeve about its longitudinal axis without varying the size of the aperture.

UNITED STATES PATENTS References Cited in the file of this patent 1,801,370 Schmidt Apr. 21, 1931 1,889,816 White Dec. 6, 1932 2,357,527 Lundquist Sept. 5, 1944 2,786,420 Kenney Mar. 26, 1957 FOREIGN PATENTS 606,328 Great Britain Aug. 11, 1948 

